The students of Class 1 - A would have a range of reactions. Ochaco might find the romantic elements in the fanfiction really sweet, especially if there are any cute ship moments. Iida would likely be concerned about whether the fanfiction adheres to some sort of moral code. He might be nitpicky about things like fairness and justice within the fictional story.
Shigaraki would likely be dismissive. He's so focused on his own goals of destroying the hero society that he'd see fanfiction as a useless distraction. However, if there were elements in the Genshin Impact fanfic that could somehow be related to his own plans, like powerful artifacts or magic that could be used for destruction, he might take a second look.
The characters would have a range of reactions. Some would be in disbelief. They have witnessed Deku's journey from a quirkless boy to a powerful hero - in - training. So, seeing him as a villain in a fanfiction would be like a complete 180 - degree turn. Midoriya's mother would be devastated. She has always supported her son, and to see him as a villain would go against everything she believed in. The teachers at U.A. would be concerned and start to analyze what could have led to this change. Maybe they would question their own teaching methods or if there were any signs they missed during Deku's time at the school.
Well, Bakugo might scoff at first. He'd probably think Batman is too brooding and not as straightforward as he likes his heroes. But then as he reads more of the fanfiction, he might grudgingly admit that Batman's detective skills are cool. Deku, on the other hand, would be super interested. He'd be analyzing every move Batman makes in the fanfiction, taking notes in his head about Batman's strategies and how they could be applied in his own hero work. Uraraka would be more focused on the relationships in the fanfiction. She'd be all 'aww' at the cute moments and feel for the characters when they're in trouble.
Well, some of the characters might be really excited. Deku, for example, would probably be super interested in the different powers and hero concepts in Marvel fanfiction. He might take notes on how Marvel heroes use their powers and try to find ways to apply similar ideas to his own hero journey.
Well, I think some of the MHA characters would be really confused. For example, Midoriya might be a bit bewildered by the different superpower concepts in the MCU fanfiction. He's used to his own world's Quirks, and suddenly seeing things like the Infinity Stones and Asgardian magic would be a lot to take in.
On the other hand, Bakugo might be enraged. He's a prideful character and if the fanfiction misrepresents him or shows him in a way he doesn't like, he could get really angry. He might even go on a rant about how inaccurate it is compared to his real self and his ideals of heroism. Also, if the fanfiction portrays him as weak, that would definitely set him off.
The heroes in MHA like All Might might view Dabi fanfiction with a sense of concern. All Might has always been about justice and the greater good. He might see Dabi fanfictions as a sign of how some people are attracted to the darker side of the hero - villain dynamic. He could worry that it might influence younger fans in the wrong way. However, villains in MHA might have different reactions. Shigaraki could see Dabi fanfictions as a way to understand how the public perceives Dabi and use that knowledge to his advantage in his evil plans.
If the My Hero Academia characters were to react to Spy x Family fanfiction, it would be quite a spectacle. Momo Yaoyorozu could be impressed by the creative plots in the fanfiction. She might admire how the Spy x Family world is built with its own set of rules and characters. Kirishima would likely be excited by the action scenes. He'd be all about the times when Loid has to fight or use his spy skills. And Mineta? Well, he might have some inappropriate thoughts, but we'll just ignore that and focus on the more positive reactions of the other characters.
They may be either amused or annoyed. It depends on how they are portrayed in the fanfiction. If it's a positive and creative portrayal, they might be amused. But if it's a negative or inaccurate one, they could be annoyed.
Some characters might be very intrigued. For example, Albedo, with his scientific mind, would likely analyze the concepts in the fanfiction related to Earth. He'd be interested in how Earth is depicted, its cultures, and technologies. He might even try to find similarities with Teyvat in terms of elemental powers or social structures.